Duplicating records to fill gap between dates

Question

I need to do something really weird, which is to create fake records in a view to fill the gap between posted dates of product prices.

Actually, my

Answer 1

You can create a row generator statement using the CONNECT BY LEVEL syntax, cross joined with the distinct products in your table, and then outer join that to your prices table. The final touch is to use the LAST_VALUE function and IGNORE NULLS to repeat the price until a new value is encountered, and since you wanted a view, with a CREATE VIEW statement:

create view dense_prices_test as
select
    dp.price_date
  , dp.product
  , last_value(pt.price ignore nulls) over (order by dp.product, dp.price_date) price
from (
      -- Cross join with the distinct product set in prices_test
      select d.price_date, p.product
      from (
            -- Row generator to list all dates from first date in prices_test to today
            with dates as (select min(price_date) beg_date, sysdate end_date from prices_test)
            select dates.beg_date + level - 1 price_date 
            from dual
            cross join dates
            connect by level <= dates.end_date - dates.beg_date + 1
            ) d
      cross join (select distinct product from prices_test) p
     ) dp
left outer join prices_test pt on pt.price_date = dp.price_date and pt.product = dp.product;